1. Technical Field
The present invention relates to an electromagnetic drive system that is suitable for moving an object, such as an optical and/or electrical reader/writer, along at least one motion axis.
2. Related Art
Electromagnetic drive systems are used in a wide variety of applications. One such application involves the use of an electromagnetic drive to properly orient a reading and/or writing component of a storage device, such as the objective lens of an optical reader, with respect to the storage media. The electromagnetic drive system used in such storage devices may direct the reading and/or writing component radially with respect to the storage media in a tracking direction, perpendicularly with respect to the storage media in a focusing direction, and/or rotationally to compensate for tilting errors between the reading and/or writing component and the storage media.
The electromagnetic drive system used in such storage devices may include multiple magnets that are fixed on a base. The magnets may be multiple pole magnets, such as 8-pole magnets, that are arranged so that a pole of a first magnet faces the opposite pole of a second magnet. Printed circuit boards may be disposed between the magnets and mounted so that they are movable with respect to the base along a tracking axis, a focusing axis, and/or a tilting axis. Magnetic circuits on the surface of the printed circuit boards are actuated while in the magnetic field of the multiple pole magnets to generate motion along the various axes. The magnetic circuits may be wound coils disposed on the surface(s) of the printed circuit boards and/or may be in the form of wound conductive lines formed on the surface(s) of the printed circuit boards.
The formation of the magnetic circuits on the surface(s) of the printed circuit boards may be complicated. Multiple layers of complex wound conductive lines may be required in some instances. Further, the magnetically active domains of the multiple layers of wound conductive lines may be small in comparison to the overall area used to form the magnetic circuit. This may result in a less than optimal use of space.